The invention relates to an assembly of at least two detachably superposed annular anti-implosion bands.
The invention also relates to an anti-implosion band for such an assembly.
The invention further relates to a display tube comprising such an anti-implosion band.
A display tube, which generally comprises an evacuated envelope having a substantially rectangular display window, can be used in black and white, colour and projection television, as well as in the display of digits and letters (Data Graphic Display) and in other apparatus in which a display tube is used.
To preclude implosion of the display tube, the envelope is customarily provided with an anti-implosion band. In particular, annular metal bands called shrink bands are used for this purpose, which are provided around the display window in a heated state and, after cooling, secure the display window under a mechanical stress.
In general, the anti-implosion bands are manufactured separately from the envelopes in large numbers, and have to be stored and/or transported before they can be provided around the envelopes. In practice however, it appears that storing and/or transporting anti-implosion bands can sometimes lead to deformation of the bands.
Deformation of an anti-implosion band is undesirable because it may give rise to problems when securing the anti-implosion band around the display tube and, in some cases, it may even lead to fracture of the envelope during the cooling of the anti-implosion band.